This is a very rough description of a fiberglass seat pan that I have mounted on my bike.
The system consist of three parts, a bottom seat pan, a top seat pan, and a seat
The short view is that it acts as an inverted fiberglass bow.
The two halves of the seat pan base are connected at both the front and back, with the back being thinner. As weight and pressure increases on the top plate it forces the back end to move forward making the distance shorter. This causes the top plate to draw the bottom plate inward at the back. As pressure returns to normal, the fiberglass “spring” returns to the original shape with the top plate rising back up and the rear end straightening back out.
The seat itself has a bit of flex and is mounted to the seat pan at three points with rubber washers.

I have only had it on for a few days and I feel sure it will need some serious tweaking, but the concept seems to work. The overall give is probably less than an inch.
I got expensive shocks on the bike, but a rigid seat and a quick pothole equals an instant migraine.
Once I get the bugs worked out I will finish the glass out and cover the seat with foam and leather.

My first discovery was that my Butt is a lot bigger than I thought it was…I got to add some inches to my handmade seat!
I will update you as I learn more."

"Springs! We don't need no stinking Springs!!!

JohnBoy wrote on 11/29/10 at 20:47:00:


Don't you hate that discovery - for me it's usually when i see a picture somebody took - i guess i subconciously turn my "good side" toward all mirrors  

Seat idea looks cool - how do you make that out of fiberglass?

As I said this is a 'work in progress', and I am discovering that I am not much of an engineer. I did discover "and correct" a major flaw.
The top seat pan, "the string of my bow"is the part that my seat is fastened to. I had the seat connected by three bolts extending from the bottom of the seat through the top seat pan. two in the back and one at the seat's 'horn'. This did a wonderful job of folding the seat on, but the rigid seat prevented the front two thirds of the spring from flexing.
The solution was to replace the front bolt with a steel tongue that slides through a bracket on the front of the seat pan. Now as the spring seat pan flexes the seat can move backword and forward with it. This allows the entire length of the seat pan spring to flex.




I spent about an hour riding some of the worst streets in my part of town hunting for bumps. Streets that I avoided at all cost were no problem! I tried real hard 'not' to protect myself and to take all bumps and potholes head on...an hour later I was convenced.
Now it is time to build one more version. This one will be cleaner, stronger and lighter...and it will fit my ample butt a lot better.
I will provide pictures of the finished product but it might not happen until after the holidays.

Thanks for the feedback
JohnBoy

I will be happy to share what I have done and how I did it...but labor is on you